Flying Through the Solar System
Grades 4-6

In this lesson students will study the Solar System, with emphasis on the terrestrial planets.
They will be involved in hands-on activities to model information about Mercury, Venus,
and Mars. To depict the size of the Solar System, students will create a model of it out of
candy. They will also write a book about their travels through the Solar System, beginning
at age ten and reaching Pluto at age seventy.

LOOK UP:#9 Mercury, Venus, and Mars

Students will be able to:

Describe and compare the terrestrial planets of the Solar System

Devise several products, such as graphs and models, to compare objects in the Solar System.

One large card-stock postcard

A Space Learning Log (paper booklet with entries for Mercury, Venus, and Mars)

Long ago people thought that the Sun, Moon, and planets all moved around the Earth. If
you watch the sky over a long period of time, it might seem that everything does revolve
around the Earth. You see the Sun rising in the east and setting in the west every day. You
can see that the Moon gradually moves eastward day by day (or, rather, night by night),
changing its shape.
Most people believed this. This idea is call the "geocentric system." Only a few people
believed that the Earth and other planets revolve around the Sun. Copernicus in 1514 and
Galileo in 1609, however, said, correctly, that the Earth and the planets revolve around the
Sun. (The Moon does revolve around the Earth.)

Mercury:
Mercury is the hottest planet and the one closest to the Sun. It takes 88 days for Mercury to
travel around the Sun. One day on Mercury is equal to 59 Earth days. Mercury is slightly
larger than our Moon. We can take pictures of its surface with satellites because it does not
have an atmosphere. It has no moons. Its temperatures range from 800 degrees F in sunlight to -
300 degrees F in the dark.

Venus:
Venus is about the same size as the Earth. It is covered with clouds that are so thick that its
surface is not visible through a telescope. It often appears to us in the evening or early
morning sky, looking like a bright, white star. Its atmosphere is mostly sulfuric acid and
carbon dioxide. The Sun's heat is trapped by Venus's clouds, so the temperature on the
surface is about 900 degrees F. If you landed on Venus, you would be dissolved, roasted, or
crushed by its atmosphere. There are mountains and lowlands on its surface. This planet
rotates once every 243 Earth days and travels around the Sun in 225 days. Venus has no
moons.

Earth:
From space, the Earth looks like a beautiful, blue jewel. Our atmosphere protects us from
the Sun's heat and harmful rays, permitting just the right amount of sunlight through to
provide plants with the energy to grow. About 70% of the Earth is covered with water.
Some of the water is frozen in polar ice caps in the Arctic and Antarctica. We are located in
the "life zone" of the Solar System. Our planet is not too hot or too cold for life to exist.
The Earth rotates once every 24 hours and takes about 365 days to travel around the Sun.
There is one moon orbiting our planet.

Mars:
Mars looks like a red star in the night sky. The red color comes from the rocks on Mars's
surface. The rocks have a great deal of iron in them that rusts in the moisture in Mars's
atmosphere. Mars has a thin atmosphere, and it is only about half the size of Earth. Its year
lasts 687 days. It has two moons. Mars has polar ice caps and seasons that change as it
revolves around the Sun. Two unmanned satellites, Viking I and Viking II, landed on Mars
in 1975. They photographed the surface, recorded the temperature, and tested the soil. No
life was found on the planet, but pictures show signs that there was once running water
there. The water is now frozen in the soil and polar ice caps of the planet.

Ask the students if they believe it will someday be possible for us to live on other planets in
our Solar System. Ask them to list in their Space Learning Logs three different ways in
which the terrestrial planets are like the Earth. Have them list facts that they discover about
the planets Mercury, Venus, and Mars.

START the video LOOK UP: Mercury, Mars, and Venus.

STOP the video for the students to participate in the activity that demonstrates the
gravitational force of the Sun compared to the speed of the planets. Have the students attach
an eraser to a piece of string. Pass the string through the straw. Attach a weight to the other
end. Explain that this is a good model for understanding the Sun's gravitational force. The
eraser represents a planet. The weight and string represent the inward pull of gravity from
the Sun. As students twirl the string at different speeds, they will be able to see why the
planets closest to the Sun move so quickly.

RESUME the video where the word "Mercury" appears.

STOP where Imagination says,
"Well, I don't see anyone living on Mercury. Those extreme temperatures would put
anyone off." Have the students record facts they learned about Mercury during this
segment of the video in their learning logs. Explain that Mercury has an elliptical orbit. All
the planets move around the Sun in orbits resembling ovals, or ellipses. Most planets
follow very rounded ellipses, but Mercury's orbit is quite elongated. Have the students try
to draw their own ellipse by doing the following:

Draw a five-inch-long line on a piece of foam core. At each end of the line, stick a pushpin into the foam core. Tie the string into a loop.

Put the loop of string around the pushpins. Place the pencil inside the loop, and pull it tight. Move it around the pins to draw an ellipse.

During the next section of the video, ask students to list how Venus and the Earth are alike
and how they are different.

START the video where Imagination says, "Let's have a look
at Venus."

STOP the video when Imagination says, "I don't see any creatures on Venus.
All those clouds sound dreary."

Venus Activity:
Explain to the students that although Venus is almost the same size as the Earth, Venus is
totally different. Its air is unbreathable carbon dioxide and pushes down with a force that is
90 times stronger than the Earth's atmospheric pressure. The atmosphere traps the Sun's
heat, raising the planet's surface temperature to 870 degrees F. The surface is so hot that it glows
in the dark.

Do the experiment from the video on making carbon dioxide, which is prominent in the
atmosphere of Venus, as follows:

Begin by having the students put baking soda in the bottom of a flask or empty plastic soda
bottle. Have them put vinegar in the balloon and attach it to the mouth of the bottle. Shake
the bottle slightly. The balloon will soon expand. Explain to the students that it is filling
with carbon dioxide gas, the same type of gas that forms a very thick layer covering Venus.

Next, ask to students to listen closely to the next section of the video to see if they can
discover why Mars looks so red.

RESUME the video where the word "Mars" appears.

STOP the tape where Imagination says, "Well, there are two rocky moons, but there is no
life there either." Have the students record facts they learned in the video segment in their learning logs. Next do the Mars Activity.

Mars Activity:
The surface of Mars looks red because it is composed of large amounts of iron. The
moisture in the atmosphere causes the iron to rust. For a simulation of the surface, have the
students make rust by combining vinegar and liquid bleach and adding a small piece of steel
wool. (The steel wool will rust very quickly.)

RESUME the video where the animated Mercury, Venus, and Mars sing to explain why life cannot exist on them.

Make an edible model of the Solar System by covering a paper plate with a very thin layer
of icing. Have the students choose different kinds of candy to represent the Sun, planets,
and asteroid belt in the Solar System. Challenge them to think creatively. Have them draw
their model of the Solar System in their learning logs and explain why they chose each
piece of candy.

Continue a study of the Solar System. Have the class create a large wall mural of the Solar
System, with written charts to explain what they learned. Hang the mural in the hall of the
school or in a public building. Encourage students to write to NASA to ask questions about
space.

Language Arts:
Have students write a story or a small book as if they are keeping a log while traveling
though the Solar System. They begin their travels on the Sun at age 10. Their journey
needs to end on Pluto at age 70. Tell them to include as much factual information about
each planet as possible.

They are traveling at a constant speed such that they will reach the planets at the following
ages (assuming they don't spend long on each planet looking around):